The present invention relates, in general, to rotary clamps, and more particularly, to a rotary clamp having an adjustable pre-stop that allows for incremental adjustments of a clamp arm in a clamped position.
Rotary clamps are known of the type in which linear actuator reciprocating movement is adapted to be translated into rotary movement of a clamp arm. The linear actuator is powered by a fluid motor, and a linkage assembly converts the linear actuator movement into rotary motion of the clamp arm. The clamp arm typically clamps a workpiece against a workpiece engaging surface. Thus, it is critical that the clamp arm repeatedly and accurately position itself in a clamped position.
It is known to utilize positive stops or pre-stops to prevent the clamp arm from exceeding a predetermined position. It is also known to utilize an eccentric pre-stop that may be rotatably adjusted to cooperatively engage the clamp arm in the clamping position. The eccentric pre-stop may be rotatably adjusted to eliminate any variation in the arm position due to a loose linkage mechanism. However, the eccentric pre-stops of past designs provide an infinite number of clamping positions for the clamp arm thereby making it difficult to utilize repeatable settings on the pre-stop. In addition, the eccentric pre-stop may be susceptible to rotational movement should the fastener that holds the eccentric pre-stop become slightly loose.
It would be desirable to provide an adjustable pre-stop that provided predetermined positions corresponding to various rotary positions of the clamp arm in the clamped position. In addition, it would also be desirable to provide an adjustable pre-stop that was not susceptible to rotational movement upon the loosening of its fastener.
The present invention overcomes the above-noted shortcomings by providing a rotary clamp having an adjustable pre-stop. The rotary clamp includes means for converting linear actuator motion between a first position and a second position into rotary clamp motion between an unclamped position and a clamped position, respectively. The converting means is disposed within a housing of the rotary clamp wherein the housing provides at least one shaped aperture formed therein. A substantially cylindrical member having a longitudinal axis has at least one shaped surface for matingly engaging the shaped aperture in the housing. The cylindrical member also provides an eccentric outer portion relative to the longitudinal axis for engaging the converting means to prohibit said converting means from moving beyond the clamped position. The eccentric outer portion creates a plurality of predetermined radial distances extending from the longitudinal axis of the cylindrical member. The radial distances correspond to predetermined rotational positions of said shaped surface within the shaped aperture of the housing wherein said predetermined radial distances correspond to predetermined incremental angular adjustments of said converting means in said clamped position. An indicia may be provided on the shaped surface of the cylindrical member to indicate the position of the cylindrical member relative to the shaped aperture in said housing.
Other options and features of the invention will become apparent by reference to the following specifications and drawings.